The book develops the concept of world citizenship education, drawing on German and Japanese traditions of educational thought to offer new perspectives on cosmopolitanism and global citizenship. It argues that education must prepare future generations for international cooperation and solidarity in facing crises like war, migration, and climate change. Unlike global citizenship education, which is tied to problematic notions of globalization, world citizenship education uses the idea of world (German: 'Welt', Japanese: 'sekai') as a relational framework linking humans, culture, society, and nature. Based on a German-Japanese collaboration, the eleven chapters explore empirical, historical, and theoretical approaches to world citizen education for educators working in international contexts.